Download Chest and Abdomen Advanced Imaging

Chest and Abdomen Advanced Imaging
By Prof. J. Stelmark
Review
Expiration
Inspiration
INSPIRATION AND EXPIRATION
Occasional exceptions have been noted
to taking chest radiographs on full
inspiration only. For certain conditions,
comparison radiographs are taken on
both full inspiration and full expiration.
Indicators for this include a possible small
pneumothorax (air or gas in the pleural
cavity), fixation or lack of normal
movement of the diaphragm, the
presence of a foreign body, and the need
to distinguish between an opacity in the
rib and one in the lung. When such
comparison radiographs are taken, they
should be labeled “inspiration” and
“expiration.”
AP LORDOTIC PROJECTION: CHEST
Pathology Demonstrated
Projection is performed primarily to rule out calcifications and masses beneath the
clavicles.
Technical Factors:
110 to 125kV range
Shielding
Secure lead shield around waist to shield gonads.
Patient Position
• Patient standing about 1 foot (30 cm) away from IR and leaning back with
shoulders, neck, and back of head against IR
• Both patient's hands on hips, palms out; shoulders rolled forward
Part Position
• Center midsagittal plane to CR and to centerline of IR.
• Center cassette to CR. (Top of IR should be about 3 inches [7 to 8 cm] above
shoulders on average patient.)
Central Ray
• CR perpendicular to IR, centered to midsternum (3 to 4 inches [9 cm] below jugular
notch)
• SID of 72 inches (180 cm)
PA PROJECTION: CHEST
Ambulatory Patient
Pathology Demonstrated
When performed erect, PA demonstrates pleural effusions, pneumothorax,
atelectasis, and signs of infection.
Part Position
• Align midsagittal plane with CR and with midline of IR with equal margins
between lateral thorax and sides of IR.
• Ensure no rotation of thorax by placing the midcoronal plane parallel to the IR.
• Raise or lower CR and IR as needed to the level of T7 for average patient. (Top
of IR will be approximately 1½ to 2 inches [4 to 5 cm] above shoulders on
average patients.)
Central Ray
• CR perpendicular to IR and centered to midsagittal plane at level of T7 (7 to 8
inches [18 to 20 cm] below vertebra prominens, or to the inferior angle of
scapula)
• SID of 72 inches (180 cm)
Respiration
Exposure made at end of second full inspiration.
LATERAL POSITION: CHEST
Ambulatory Patient
Pathology Demonstrated
A 90° perspective from PA may demonstrate pathology situated posterior to the
heart, great vessels, and sternum.
Central Ray
• CR perpendicular, directed to midthorax at level of T7 (3 to 4 inches [8 to 10
cm] below level of jugular notch)
• SID of 72 inches (180 cm)
LATERAL POSITION: UPPER AIRWAY
Pathology Demonstrated
Pathology is of the air-filled larynx and trachea, including the region of thyroid
and thymus glands and upper esophagus for opaque foreign object or if contrast
medium is present. Soft tissue lateral frequently is taken to rule out epiglottitis,
which may be life threatening for a young child
Central Ray
• CR perpendicular to center of IR at level of C6 or C7, midway between the
laryngeal prominence of the thyroid cartilage and the jugular notch
• SID of 72 inches (180 cm), if possible, to minimize magnification
Respiration
Make exposure during a slow, deep inspiration to ensure filling
trachea and upper airway with air.
Collimation and CR:
• Collimation borders should appear on both sides with ideally only minimal (¼
inch or less) borders on top and bottom. • The collimation field (CR) should be
centered to the area of T1-2.
Exception: semiaxial erect AP.
Exception: semiaxial supine AP.
If patient is weak and unstable and/or is not able to assume the erect
lordotic position, an AP semiaxial projection may be taken with the
patient in a supine position. Shoulders are rolled forward and arms
positioned as for lordotic position.
The CR is directed 15°to 20° cephalad, to the midsternum.
AP PROJECTION: CHEST
Supine or Semierect (in Department or as Bedside Portable)
Pathology Demonstrated
This projection demonstrates pathology involving the lungs, diaphragm, and
mediastinum. Determining air-fluid levels (pleural effusion) requires a completely
erect position with a horizontal CR, as in a PA or decubitus chest projection.
Shielding
Place lead shield to shield gonads.
Patient Position
• Patient is supine on cart; if possible, the head end of the cart or bed should be
raised into a semierect position (see Notes).
• Roll patient's shoulders forward by rotating arms medially or internally.
Part Position
• Place IR under or behind patient; align center of IR to CR (top of IR about 1½ inches
[4 to 5 cm] above shoulders).
• Center patient to CR and to IR; check by viewing patient from the top, near the tube
position.
Central Ray
• CR angled caudad to be perpendicular to long axis of sternum (generally requires ±
5° caudad angle, to prevent clavicles from obscuring the apices)
• CR to level of T7, 3 to 4 inches (8 to 10 cm) below jugular notch
• Minimum SID of 40 inches (100 cm) for supine.
Semi-erect
72”
For semierect position, use 72-inch (180-cm) SID if this is possible. Always place
markers on the IR or label the image to indicate the SID used; also indicate those
projections obtained, such as AP supine or AP semierect.
LATERAL DECUBITUS POSITION (AP PROJECTION): CHEST
Pathology Demonstrated
Small pleural effusions are demonstrated by air-fluid levels in pleural space, or small
amounts of air in pleural cavity may demonstrate a possible pneumothorax
Use decub marker (or arrow)
Patient Position
• Cardiac board on the cart or radiolucent pad under patient
• Patient lying on right side for right lateral decubitus and on left side for left lateral
decubitus (see Notes below)
• Patient's chin extended and both arms raised above head to clear lung field; back
of patient firmly against IR; cart secured to prevent patient from moving forward and
possibly falling; pillow under patient's head
• Knees flexed slightly and coronal plane parallel to IR with no body rotation
Central Ray
• CR horizontal, directed to center of IR, to level of T7, 3 to 4 inches (8 to 10 cm)
inferior to level of jugular notch. A horizontal beam must be used to show air-fluid
level or pneumothorax.
• SID of 72 inches (180 cm)
Part Position
• Adjust height of IR to center thorax to IR
• Adjust patient and cart to center midsagittal plane and T7 to CR (top of IR is about
1 inch [2.5 cm] above vertebra prominens).
Radiograph may be taken as a right or left lateral decubitus. To produce the most
diagnostic images, both lungs should be included on the image. For possible fluid
in the pleural cavity (pleural effusion), the suspected side should be down. Do not
cut off that side of the chest. The anatomic side marker must correspond with the
patient's left or right side of the body. The marker must be placed on the IR prior to
exposure. It is not acceptable practice to indicate the side of the body either
digitally or with a marking pen following the exposure.
For possible small amounts of air in the pleural cavity (pneumothorax), the affected
side should be up, and care must be taken not to cut off this side of the chest.
ANTERIOR OBLIQUE POSITIONS—RAO AND LAO: CHEST
Pathology Demonstrated
Pathology involves the lung fields, trachea, and mediastinal structures, including the
size and contours of the heart and great vessels.
Patient Position
• Patient erect, rotated 45° with left anterior shoulder against IR for the LAO and
45° with right anterior shoulder against IR for the RAO.
• Patient's arm flexed nearest IR and hand placed on hip, palm out
• Opposite arm raised to clear lung field and hand rested on head or on chest unit
for support, keeping arm raised as high as possible
• Patient looking straight ahead; chin raised
Central Ray
• CR perpendicular, directed to level of T7 (7 to 8 inches [8 to 10 cm] below level of
vertebra prominens)
• SID of 72 inches (180 cm)
45 deg RAO
45 deg LAO
Notes:
For anterior obliques, the side of interest generally is the side farthest from the
IR. Thus the RAO will provide best visualization of the left lung.
Certain positions for studies of the heart require an LAO with an increase in
rotation to 60°.
Less rotation (15° to 20°) may be of value for better visualization of the various
areas of the lungs for possible pulmonary disease.
45 deg RAO
45 deg LAO
POSTERIOR OBLIQUE POSITIONS—RPO AND LPO
Pathology Demonstrated
Pathology involves the lung fields, trachea, and mediastinal structures, including the
size and contours of the heart and great vessels.
Patient Position (Erect)
• Patient erect, rotated 45° with right posterior shoulder against IR for RPO and 45°
with left posterior shoulder against IR for LPO
• Arm closest to the IR raised resting on head; other arm placed on hip with palm out
• Patient looking straight ahead
Sternum RAO
Position
• Erect (preferred) or semiprone, turned 15°–20° with right side down.
(A thin-chested patient requires slightly more obliquity than a thickchested patient.)
SID: 100–110 cm (40–44″)
Collimation: Long narrow collimation field, to area of sternum
Respiration: Gentle even breathing during exposure (3-4 sec)
Lateral, erect sternum.
Pathology Demonstrated
Abnormal masses, air-fluid levels,
and accumulations of intraperitoneal
air under diaphragm are
demonstrated.
Perform erect radiograph first if
patient comes to department
ambulatory or in wheelchair in an
erect position.
LATERAL DECUBITUS POSITION (AP PROJECTION): ABDOMEN
Pathology Demonstrated
Abdominal masses, air-fluid levels, and possible accumulations of intraperitoneal air
are demonstrated. (Small amounts of free intraperitoneal air are best demonstrated
with chest technique on erect PA chest.)
Important: Patient should be on side a minimum of 5 minutes before exposure
(to allow air to rise or abnormal fluids to accumulate); 10 to 20 minutes is
preferred, if possible, for best visualization of potentially small amounts of
intraperitoneal air.
Left lateral decubitus best visualizes free intraperitoneal air in the area of the
liver in the right upper abdomen away from the gastric bubble.
70 to 80 kV range
Marker: Place arrow or
other appropriate marker to
indicate “up” side.
Patient Position
• Lateral recumbent on radiolucent pad, firmly against table or vertical grid device
(with wheels on cart locked so as not to move away from table)
• Patient on firm surface, such as a cardiac or back board, positioned under the sheet
to prevent sagging and anatomy cutoff
• Knees partially flexed, one on top of the other, to stabilize patient
• Arms up near head; clean pillow provided
Central Ray
• CR horizontal, directed to center of IR, at about 2 inches (or 5 cm) above level of
iliac crest; use of a horizontal beam to demonstrate air-fluid levels and free
intraperitoneal air
• Minimum SID of 40 inches (100 cm)
Radiographic Criteria
Structures Shown: • Air-filled stomach and loops of bowel and air-fluid levels
where present. • Should include bilateral diaphragm.
Position: • No rotation; iliac wings appear symmetric, and outer rib margins are
the same distance from spine. • Spine should be straight (unless scoliosis is
present), aligned to center of IR.